Effects of graphene nanoplatelets and hexagonal boron nitride on spark plasma sintered (Zr,Nb)B2 solid solutions

Bulk (ZrxNb1-x)B-2 solid solution systems with x ranging from 0 to 1 with intervals of 0.25, were consolidated by spark plasma sintering (SPS) at 1850 degrees C under 50 MPa with a holding time of 5 min. In addition, 1 vol% graphene nanoplatelets (GNPs) and 1 vol% hexagonal boron nitride (h-BN) were added to (Zr,Nb)B-2 solid solutions to investigate their effects on densification, mechanical properties, and optical properties. Transmission electron microscopy analysis, phase analysis, and lattice parameters confirmed the formation of a complete (Zr,Nb)B-2 solid solution. Raman analysis confirmed the structural integrity of both the GNPs and h-BN in the solid solution. The additives modified different properties of the (Zr,Nb)B-2 solid solution. Namely, the addition of GNPs increased the relative density by similar to 2% by removing oxide impurities. The highest Vickers hardness was obtained for h-BN-modified Zr0.25Nb0.75B2, which had the lowest grain size. The addition of GNPs and h-BN contributed to the improvement in toughness by activating toughening mechanisms. The h-BN-modified (Zr,Nb)B-2 exhibited the best oxidation performance. The optical absorbance of the (Zr,Nb)B-2 solid solution was higher than that of the GNP- and h-BN-modified samples. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

By adding graphene nanoplatelets and hexagonal boron nitride to the (Zr,Nb)B-2 solid solution, different properties of the solid solution were modified, such as increased relative density, improved hardness, and enhanced toughness. These additives contributed to the enhancement of the solid solution's performance by activating toughening mechanisms.